Illumination control for electric clock



Dec. 11, 1956 R. KRAMER ILLUMINATION CONTROL FOR ELECTRIC CLOCK Filed March 18, 1955 JNVENTOR.

RICHARD KRAMER 2,773,??72 i a'tented Dee. l1, 1956 2,773,972 ILLUMINATION CONTROL FUR ELECTRIC CLOCK Richard Kramer, Thomaston, Conn., assignor to General Time Corporation, New York, N. Y., a corporation Delaware Application March 18, 1955, Serial No. 495,293 7 Claims. (Cl. 240-2) The present invention relates to electric clocks and more particularly to a finger touch control for varying the illumination of the dial.

It is the primary object of the invention to provide a clock having a novel control arrangement for varying illumination which provides a maximum of convenience, enabling illumination to be varied over the entire range by lightly touching a control member. It is a related object to provide an illumination control device for a clock in which the energy required to perform the adjustment is obtained in a novel fashion from the clocks own driving motor. It is another object to provide an illumination control arrangement which does not require handling of the clock and which may be easily operated in the dark.

it is a further object to provide an illumination control for an electric clock which permits rapid and precise adjustment and which continuously and automatically recycles until fingertip pressure is released.

t is an object to provide an illumination control which is effective and possesses a high degree of sales appeal but which nevertheless is extremely simple, adding only a few cents to the cost of manufacturing a clock. It is still another object to provide a control mechanism which is of compact unitary construction, requiring but a single point of pivoting on a clock frame and which may be included in the designs of existing clocks Without necessity for costly modifications.

Other objects and advantages will be apparent upon reading the attached detailed description and upon reference to the drawings, in which:

Figure 1 shows, in partial elevation, an electric clock including an illumination device constructed in accordance with the present invention.

Fig. 2 is a plan view looking along the line 22 in Fig. 1.

Fig. 3 is a view showing the device in both engaged and disengaged position.

Fig. 4 is a schematic diagram of the electrical circuit.

While the invention has been described in connection with a preferred embodiment, it will be understood that the invention is not necessarily limited thereto but includes' such modifications and alternative constructions as may be included within the spirit and scope of the appended claims.

Turning to the drawings, an electric clock, for example, an alarm clock, to which my invention is applicable, is shown in outline at 10, having a dial 11 and minute and hour hands 12, 13. The electric motor and driving train for driving the hands is conventional and it will suffice to say that a constantly running motor 14 mounted in a clock frame 15 drives a train of speed-reducing gears, one of which is indicated at 16.

For providing illumination, a lamp bulb 18 is mounted in one corner of the clock casing, current for the bulb being supplied by an auxiliary winding 19 (Fig. 4) in the magnetic structure of the motor. To shield the bulb and to direct the light onto the dial a suitable shield may, of course, be provided.

In accordance with the invention a rheostat is provided having a resistance element which is adjusted by manually coupling it, under fingertip control, to the regular driving train of the clock. The rheostat, indicated at 20, has a subframe including a pair of side plates 21, 22. Integrally formed in the plate 21 are a pair of spaced arms 21a, 21b mounting an insulating form 23 carrying a wire wound resistance element 24. Riding upon the resistance element 24 is a resistance changing member or slide 25. The latter is made in the form of a gooseneck from resilient metal and includes a base portion 26 mounted on a sliding block 27 by suitable screws 28, 29. The block is dimensioned to slide freely between the two side plates 21, 22. For the purpose of guiding the block in its endwise movement, it is mounted on a reciprocating rod or plunger 30, being secured to the middle portion thereof by a transverse pin 31. The ends of the plunger are slidably received in a pair of alined holes formed in guides 33, 34 at the respective ends of the side plate. The guides serve not only to guide the plunger but also as spacers or bridging members to join the two side plates and to keep them properly spaced from one another.

For the purpose of positioning the plunger 30, a cam 38 is rotatably mounted at the left hand end of the rheostat and between the side plates, the plunger being kept in engagement with the cam by a coil spring 39 which is telescoped over the plunger as shown. Coupled to the cam 38 and mounted outboard of the side plate 22 is a pinion 40. A pawl 41 in the form of a leaf spring is anchored at 42 and bears against the pinion 40 to insure against retrograde movement of the cam.

In accordance with one of the aspects of the invention, the subframe is pivoted at one end for bodily swinging movement to bring the pinion 4% into engagement with the gear 16 in the driving train, the pivoting being accomplished in the present instance by a pin 43 which engages alined spacers or supports 44 on the clock frame. Pivoted to the arm 2112 by a screw 45 and extending upwardly therefrom is a manual operator in the form of a rod 46 having a suitable knob or button 47 at its outer end. The button is kept outwardly extended and the rheostat is kept disengaged from the gear 16 by a return spring 48.

It will be apparent from the above that the rheostat may be adjusted simply by applying fingertip pressure to the button 47 thereby swinging the rheostat frame downwardly into the position shown in Fig. 3 and meshing the pinion with the constantly running gear 16. This causes the rod 30 carrying the slide 27 to be cammed endwise producing progressive dimming of the lamp bulb. As soon as the proper point of illumination is reached, pressure is released and the pinion springs free of the driving gear. After disengagement no further change in resist- ;ance can occur since the cam is locked in position by the pawl 41.

In the event that finger pressure is maintained, the dropofi point on the cam is reached which returns the illumi nation to full brilliance and the cycle is repeated indefinitely without any damage to the rheostat mechanism. The gear in the driving train which is selected to drive the pinion depends upon the factors of speed and accessibility. The speed is not critical and even a low torque gear may be used, with proper choice of pinion diameter, without imposing undue loading upon the driving motor usually provided in clocks. I

Because of the compact unitary construction the device may be incorporated into existing designs of clocks by the simple expedient of providing a pivot pin in the clock frame and means for guiding the operating plunger. As to cost, the entire unit may be manufactured in quantity for a few cents while adding substantially to the utility and sales appeal of the clock.

As to convenience, the device is especially well suited for use at bedside where it is desirable to be able to change the illumination in the dark without having to lift or manipulate the clock.

I claim:

1. In an electric clock the combination comprising a dial, means including a clock mechanism having a constantly running motor and gear train for providing time indication on said dial, a lamp bulb for illuminating the dial and arranged adjacent thereto, a source of current connected to said lamp bulb for energizing the same, a rheostat connected between the current source and the lamp bulb, clutching means engageable with said gear train for changing the setting of said rheostat, and a conveniently accessible manual operator on said clock for operating said clutching means. 2. In an electric clock the combination comprising a dial, means including a clock mechanism having a constantly running motor and gear train for providing time indication on said dial, a lamp bulb for illuminating the dial and arranged adjacent thereto, a source of current connected to said lamp bulb for energizing the same, a rheostat connected between the current source and the lamp bulb, means including a bodily movable gear pinion arranged for movement into and out of meshing engagement with said gear train for changing the setting of said rheostat, and conveniently accessible manual means coupled to the gear pinion for bodily moving the same.

3. In an electric clock the combination comprising a clock frame, a dial, a clock mechanism having a constantly running motor and gear train for providing time indication on said dial, a lamp bulb adjacent said dial for illuminating the same, a source of current for the lamp bulb, and a rheostat, said rheostat having a subframe movably mounted on said clock frame and carrying a pinion, said subframe having a manual operator extending outside the clock frame for moving the subframe for meshing of the pinion with one of the gears in the gear train, said subframe further having a resistance element connected between the lamp bulb and current source, and means including a cam driven by the pinion and coupled to the resistance element for varying the illumination as long as the manual operator is manually depressed.

4. In an electric clock the combination comprising a clock frame, a dial, a clock mechanism having a constantly running motor and gear train for providing time indication on said dial, a lamp bulb adjacent said dial for illuminating the same, a source of current for the lamp bulb, and a rheostat, said rheostat having a subframe pivoted to said clock frame at one end and having a pinion at the other end, said subframe having a manual operator extending outside the clock frame for rocking the subframe for working of the pinion and one of the gears in the gear train together with a spring for retracting the subframe when the manual operator is released, said subframe further having a resistance element connected between the lamp bulb and current source, and

means including a recycling cam driven by the pinion and coupled to the resistance element for varying the illumination as long as the manual operator is manually depressed.

5. In an electric clock the combination comprising a clock frame, a dial, a clock mechanism having a constantly running motor and gear train for providing time indication on said dial, a lamp bulb for illuminating the dial, a source of current for the lamp bulb, and a rheostat, said rheostat having a resistance element and a resistance changing member cooperating therewith, a pinion mounted for bodily movement into and out of engagement with said gear train, a cam coupled to said pinion, a cam follower riding on said cam and connected to the resistance changing member, said pinion having a manual operator arranged to bring the pinion into mesh with the gear train when the manual operator is moved, and a return spring coupled to the manual operator for unmeshing the pinion when the manual operator is released.

6. In an electric clock, the combination comprising a clock frame, a dial, a clock mechanism having a constantly running motor and gear train for providing time indication on said dial, a light source arranged adjacent said dial for illuminating the same, means including a rotatable member for varying the intensity of illumination cast upon said dial by said light source, said illumination varying means being so constructed and arranged as to provide a cyclical variation in illumination between bright and dim upon continuous rotation of the rotatable member in the same direction, a driving pinion coupled to said rotatable member and mounted for bodily movement toward and away from one of the gears in the gear train, manual means including a manual operator conveniently acessible at the outside of said clock for bodily moving said pinion into engagement with the cooperating gear in the gear train to provide driving engagement of the illumination varying means so that the illumination is cyclically varied, and means including a biasing member for unmeshing said pinion incident to manual release of the operating member for causing such illumination thereafter to remain constant at a predetermined point in the variation cycle.

7. In an electric clock, the combination comprising, a dial, a clock mechanism having a constantly running motor and gear train for providing time indication on said dial, illumination means for illuminating the dial, means including a driven member for progressively varying the illumination means between bright and dim, a clutching means interposed between said driven member and said gear train, and a conveniently accessible manual operator connected to said clutching means for clutching and unclutching the driven member to provide progressive variation in the illumination to a chosen setting.

References Cited in the file of this patent UNITED STATES PATENTS 2,036,831 Salhofer Apr. 7, 1936 2,264,198 Chak Nov. 25, 1941 2,537,971 Dames Jan. 16, 1951 2,687,470 Weisz Aug. 24, 1954 

